1. Field of the Invention
The present invention relates generally to cooling fans, and more particularly relates to the attenuation of vibration and resulting noise associated with internal computer cooling fans.
2. Description of Related Art
To prevent an interior heat buildup which could potentially damage their internal electronic operating components, various types of personal computers are typically provided with one or more internal cooling fans. Each fan normally operates while the computer is running to continuously draw ambient air into the computer housing structure through a housing air intake opening, flow the air generally across the operating components to absorb heat generated thereby, and then discharge the heated air from the interior of the housing through a suitable air discharge opening formed therein.
Despite the fact that they are usually rather small, computer cooling fans can generate an undesirable amount of vibration, and attendant housing structure vibration noise, if care is not taken to properly isolate them from the interior computer housing support structure upon which they are mounted. To this end, various fan mounting structures have heretofore been utilized in an attempt to isolate the computer housing structure from fan vibration and thereby attenuate fan vibration-created noise during computer operation.
In one conventional configuration thereof, a computer cooling fan has a rectangular frame structure in which the fan motor and impeller are operatively mounted between open inlet and outlet sides of the frame. The four peripheral walls of the frame, which border its open inlet and outlet sides, are relatively thin. However, to provide for mounting of the frame within the interior of a computer housing, the four corner portions of the rectangular frame are diagonally thickened. Small circular bores are formed through these thickened corner portions of the frame.
To mount the conventional cooling fan just described within the interior of a computer housing structure, eight resilient annular grommet members are provided, each of the grommet members having an axially projecting hollow tubular central stem portion formed thereon. At each thickened corner portion of the fan frame two of these stem portions are manually pushed into the front and rear ends of the corner portion bore so that the radially enlarged annular portions of the two grommets are positioned against the front and rear side surfaces of the frame corner portion.
The fan frame is then pushed forwardly into a rectangular plastic mounting frame having inwardly projecting pins formed on front side corner portions thereof. These four plastic pins enter the four resilient grommets on the front side of the fan housing in a manner resiliently supporting the fan within the mounting housing. With the fan installed in this manner within the mounting housing, the rectangular outer periphery of the fan frame is spaced inwardly from the rectangular inner periphery of the mounting frame, and the enlarged annular portions of the four resilient grommets on the outlet side of the fan housing project a small distance outwardly beyond the rear side of the mounting frame. The rear side of the mounting frame is then fastened against an interior side portion of the computer housing structure, over an air inlet opening formed therein, to slightly axially compress all of the resilient grommets.
As a general proposition, this method of mounting the cooling fan within a computer housing yields satisfactory performance from the standpoint of vibration and noise reduction. However, from structural and installation standpoints it has several limitations and disadvantages. For example, the manual installation of the eight resilient grommets, and the subsequent blind insertion of the mounting housing pins into the inlet side grommets, tend to be tedious and time-consuming tasks. Additionally, particularly when the fan is removed from the mounting housing, one or more of the small grommets can be easily become dislodged from the fan housing and be lost.
Another problem associated with this conventional cooling fan mounting technique is that the fan vibrational forces transmitted to the support pins on the mounting housing sometimes cause one or more of the pins to fatigue and break, thereby materially reducing the vibration isolation capabilities of the overall mounting structure. Furthermore, the four inlet side grommets provide effective vibration damping only in an axial direction.
It can readily be seen from the foregoing that a need exists for improved vibration isolating mounting apparatus for internal computer cooling fans. It is accordingly an object of the present invention to provide such improved apparatus.